Sometimes it is great for the class to listen (or watch) a story read by someone else. Here are some sites that will help.
Free sites
Storylineonline.net - stories read by famous Hollywood actors - this site has nice simple animations of the illustrations, and some of the actors have pretty good diction. Only about 20 stories here though.
Barnes and Noble Online Storytime - includes Eric Carle reading The Very Hungry Caterpillar
Read to Me Las Vegas(really!) - I admit, I didn't immediately recognise any of the stories on here.
Storynory.com - a range of fairy tales and classic tales, all just audio with the text on the same page
Reading Planet - seems to have a number of free books with animation and audio.
Speakaboos - lots of free stories here with simple animations.
Mem Reads Aloud - a small selection of Mem's stories read aloud by the author herself.
Robert Munsch - audio only, lots of stories that can be listened to online or downloaded.
Magic Keys - mostly illustrated only, some audio. I think these are stories written by independent authors for online distribution, none of the classics are here.
Paid sites
MightyBook currently costs only $29.95 per year. There are a number of free samples.
Tumblebooks.com - this site is normally by subscription but your local library may provide some access.
Lists of sites
Here are some lists in case you want to go hunting yourself. I may not have linked to some of these because they didn't suit my purposes.
Free sites
Paid sites
Lists of sites
Here are some lists in case you want to go hunting yourself. I may not have linked to some of these because they didn't suit my purposes.